REVIEWS 



Electrical Engineering. By W. Slingo and A. Brooker. New edition, 

 thoroughly revised by W. Slingo and T. F. Wall, M.Sc. [Pp. 850 + viii., 

 389 figures.] (Longmans, Green & Co. 12s. bd.) 



The success of this well-known work has necessitated some ten editions and 

 reprints since its first appearance in 1890, and it must be said at once that 

 prosperity has not dulled the authors' efforts to keep their book abreast of the 

 times. Electrical knowledge has progressed, more especially on its applied side, 

 at such an amazing rate, that a heavy burden is laid on the writers of descriptive 

 text-books who desire to do their duty by their readers. Progress entails entensive 

 additions to almost every section of a new edition, and rewriting, not mere revising, 

 has to be the treatment prescribed for much that had been offered previously. 



The electrician of to-day can scarcely complain of the way in which his wants 

 are ministered to. Treatises general and special, text-books, and "short-roads" 

 abound. Weekly journals have sprung up with mushroom-like rapidity and insist 

 on adding to his knowledge. 



The volume before us aims at giving a sound treatment of direct and 

 alternating currents, with their immediate applications. These in themselves are 

 sufficiently comprehensive to require upwards of 850 pages of closely printed 

 matter. Some 300 pages are devoted to introductory theory, together with 

 accounts of laboratory and workshop instruments ; thus, for example, the Bridge- 

 Megger, the Crompton Potentiometer, the Evershed Ammeter, the various 

 Weston instruments, and the Kelvin Volt Balance are dealt with among much 

 besides. 



Succeeding chapters discourse on alternating and direct current dynamos, 

 motors (with digressions on electric traction on the London County Council's 

 tramways and the South and Central London Railways), transformers, storage 

 ells, and arc incandescent lamps. 



General criticism can serve little purpose in dealing with a work which can 

 fairly claim to have seen active service ; but the descriptive portions of the book 

 strike us as rising in excellence above the general level of the rest. Perhaps in 

 the midst of so much that is good, we may be allowed to make a few points, not 

 so much as criticisms, but rather as suggestions. 



The otherwise admirable section on photometry cannot claim to be complete 

 without a notice of flicker photometers. More stress might well be laid on the 

 advantages of the Weston normal cell over the Clark. The electromotive force 

 of the latter, given throughout as i"434 volts, needs amending to i'433 volts — its 

 now accepted value. The H pattern of cell should replace the one mentioned as the 

 standard form. Stress is not laid on the fact that Ohm's law merely embodies the 

 results of experiments with metallic conductors, and that through its existence we 

 need to define as primary only two of the three units of current, resistance and 

 electromotive force, the two taken being those of current and resistance. Manganin 

 should most certainly be added to the description of alloys suitable for resistance 

 coils. 



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